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Section 4: Glossary of Control Functions
Alarm Annunciation
The RAC2-8 provides the following alarm annunciation mechanisms:
• Audible indication (horn).
• A lighted ‘Alarms Present’ front panel indicator.
• Activation of the Common Alarm relay output.
• Display of alarm messages on the front panel LCD.
Warnings activate the ‘Alarms Present’ indicator and a message on the
LCD, but no audible alarm or Common Alarm.
When an alarm occurs the LCD immediately displays a message (unless
an Override screen is being displayed). Pushing the Alarms
Present/Silence pushbutton acknowledges the alarm and silences the
alarm horn. The alarm message is displayed until the alarm is
acknowledged (silenced). After the alarm is silenced, normal status
display scanning resumes.
Any alarms present are displayed during scanning of normal display
pages. If more than 4 alarms are present additional pages of alarms are
created as necessary. Up to 20 alarms are stored in a First-In-First-Out
sequence.
Alarm Communications
EIA-232 Terminal Port—Transmits Alarm with time stamp.
EIA-232 Modem Port—Dials out alarm.
Both EIA-232 ports are compatible with SS-AMS (SiteScan Alarm
Management System).
EIA-422 (proprietary) to SiteScan monitoring system.
Alarm Delay
Delay before an alarm is annunciated (false alarm delay). This delay
begins on the occurrence of an alarm condition in a unit. If the alarm
condition has not corrected itself by the end of the delay period, the
alarm is annunciated and an autochangeover to the standby unit Occurs.
If a unit is programmed to shutdown on an alarm, the unit shuts down
when the alarm is annunciated. The Alarm Delay timer counts both up
and down and an active Alarm Delay timer can be monitored at the
display. The Alarm Delay is user selectable from the display. Range -
0.1 to 60 minutes, in increments of 0.1 minute (6 sec).
Autochangeover
If an alarm occurs in a Running unit, a Standby unit in the same zone is
started. The Running unit in alarm is stopped if it is programmed to shut
down, and the Standby unit is started. The Standby unit changes status
to become the Running unit and remains running until the Alarm is
manually cleared. Messages are written to the terminal to record the
status changes. Status screens show new unit status at the local display.
After a changeover, the newly started unit may briefly have a High
Temp or other alarm. A user selectable Hold Delay begins when any
28 • User Manual (9/97)